This invention relates to the compound methyl 3-azido-4-C-cyano-2,3,4,6-tetradeoxy-.alpha.-D-arabino-hexopyranoside (VI) and its utility in the synthesis of the known antibiotic (+)-thienamycin (I). ##STR1##
This invention also relates to processes for preparing VI from methyl 3-azido-2,3,6-trideoxy-.alpha.-D-arabino-hexopyranoside (IV). The following scheme is representative of such processes: ##STR2## As described below, the process proceeding from starting material II, via the intermediate 3-azido-3-deoxy sugar IV and 4-bromo-4-deoxy sugar V, performs a regioselective p-toluenesulfonylation of the C-3 hydroxyl of starting material II to give tosylate III; a replacement of the C-3 tosylate with an azido function with retention of configuration at C-3 to afford IV; and two inversions of configuration at C-4 of IV with a net retention of the .alpha.-D-arabino stereochemistry in VI.
The utility of the resulting compound VI in the chiral total synthesis of thienamycin is described in copending, commonly assigned, concurrently filed U.S. patent application Ser. Nos. 248,177, now U.S. Pat. No. 4,384,998; 248,176, now U.S. Pat. No. 4,324,900; and 248,174; which are incorporated herein by reference to the extent that they describe the utility of compound VI. Also incorporated by reference is U.S. patent application Ser. No. 112,058 filed Jan. 14, 1980, now abandoned, which describes the total synthesis of thienamycin and which proceeds from an intermediate species which is common to the instant disclosure and as described in the three previously mentioned, concurrently filed U.S. patent applications. Also incorporated by reference are U.S. Pat. No. 4,234,596 (issued Nov. 18, 1980), and EPO Application No. 79,101,307-1 (publication No. 0007973 filed May 1, 1979), which publications disclose schemes of total synthesis which can be fed by common intermediates made available by the presently disclosed and claimed processes.